Artificial intelligence laundry treatment apparatus and method of controlling the same

ABSTRACT

Disclosed is an artificial intelligence laundry treatment apparatus including a washing tub configured to receive laundry, the washing tub being configured to be rotatable, a motor configured to rotate the washing tub, a controller configured to control the motor such that the washing tub is accelerated to a predetermined target speed at an acceleration gradient of 1.5 to 2.5 rpm/s within a range within which the laundry moves in the washing tub, and a current sensing unit configured to sense current of the motor, wherein the controller is configured to obtain at least one of laundry weight or laundry quality from output of an output layer of an artificial neural network pre-trained based on machine learning using a current value sensed by the current sensing unit during accelerated rotation of the washing tub as input of an input layer of the artificial neural network.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of priority to Korean Application No. 10-2018-0103077, filed on Aug. 30, 2018, the contents of which is hereby incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a laundry treatment apparatus that senses laundry weight and laundry quality based on machine learning and a method of controlling the same.

Description of the Related Art

A laundry treatment apparatus is an apparatus that treats laundry through various operations, such as washing, rinsing, spin drying, and/or drying. The laundry treatment apparatus has a washing tub, which is rotated by a motor.

The laundry treatment apparatus is generally equipped with an algorithm for sensing the weight of laundry (or laundry weight) introduced into the washing tub. For example, Conventional art 1 (Korean Patent Application Publication No. 10-2006-0061319) discloses a method of calculating information, such as an eccentric value, DC voltage, and a motor torque value, obtained while performing control such that a motor is rotated at a uniform speed after the motor is accelerated to a predetermined rate of rotation using the following mathematical expressions in order to sense laundry weight.

Laundry weight value=average of current amount in constant speed period+DC voltage compensation value−eccentric compensation value+a

(a being a constant acquired through experimentation)

DC voltage compensation value=(DC voltage sensing value−b)×t

(b being an experimental constant and t being time during a constant speed period)

Eccentric compensation value=eccentric value in constant speed period×d

(d being an experimental constant)

In Conventional art 1, many constants are used to estimate the laundry weight value, and most thereof are experimental values, whereby expert settings are required, and setting values are not accurate. Consequently, Conventional art 1 has a limitation in improving accuracy in sensing the laundry weight.

Also, in Conventional art 1, setting values (experimental constants) must be accurately found in order to improve accuracy in sensing the laundry weight, which may require lots of time.

Conventional art 2 (Korean Patent Application Publication No. 1999-0065538) discloses a method of measuring time necessary to accelerate a motor to a predetermined speed and variation in the rotational speed of the motor while the motor is rotated at the predetermined speed in order to sense laundry weight.

In Conventional art 2, the measured time and variation in the rotational speed of the motor are compared with a predetermined laundry weight sensing comparison value in order to sense whether the laundry weight is large or small. The values are simply compared with each other in terms of size in order to sense the laundry weight. That is, it is only possible to distinguish between large laundry weight and small laundry weight. Consequently, Conventional art 2 has a limitation in accurately sensing various kinds of laundry weight. In addition, even in Conventional art 2, a person must find all setting values in advance for comparison, which is troublesome.

In the case in which laundry weight is not accurately measured, lots of time is necessary to perform a spin-drying operation, which is performed at a high speed. As a result, a total washing time is increased, whereby energy consumption is increased. For these reasons, various research on a method of accurately sensing laundry weight has been conducted.

Meanwhile, in recent years, interest in artificial intelligence and machine learning, such as deep learning, has increased. Classification, regression, and clustering models based on statistics are located in the center of conventional machine learning. Particularly, in supervised learning of the classification and regression models, a person defines, in advance, characteristics of learning data and a learning model that distinguishes between new data based on the characteristics. Unlike this, deep learning is a computer finding and distinguishing between characteristics by itself.

One of the factors that accelerate the growth of deep learning is an open source deep learning framework. For example, examples of the deep learning framework include Theano from Montreal University in Canada, Torch from New York University in USA, Caffe from University of California, Berkeley in USA, and TensorFlow from Google.

As the deep learning framework is open, a learning process, a learning method, and extraction and selection of data used for learning become further important for effective learning and recognition in addition to a deep learning algorithm. In addition, research on the use of artificial intelligence and machine learning in various kinds of products and services has been increasingly conducted.

PRIOR ART DOCUMENTS Patent Documents

-   1. Korean Patent Application Publication No. 10-2006-0061319     (published on Jun. 7, 2006) -   2. Korean Patent Application Publication No. 1999-0065538 (published     on Aug. 5, 1999)

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a laundry treatment apparatus capable of rapidly and accurately sensing laundry weight and/or laundry quality based on machine learning and a method of controlling the same.

It is another object of the present invention to provide a laundry treatment apparatus capable of optimizing the acceleration gradient of a washing tub such that the movement of laundry is clearly classified by laundry weight or by laundry quality during accelerated rotation of the washing tub in order to sense laundry weight/laundry quality and a method of controlling the same.

It is another object of the present invention to provide a laundry treatment apparatus capable of efficiently processing data used to determine laundry weight and/or laundry quality in order to reduce the quantity of data necessary for determination and a method of controlling the same.

It is another object of the present invention to provide a laundry treatment apparatus capable of classifying laundry based on various criteria, such as the softness/hardness of the laundry, the water content of the laundry, and the volumetric difference between dry laundry and wet laundry, and a method of controlling the same.

It is a further object of the present invention to provide a laundry treatment apparatus capable of improving accuracy in classifying laundry with accumulation of training data (motor current data) of machine learning and a method of controlling the same.

In accordance with an aspect of the present invention, the above and other objects can be accomplished by the provision of a laundry treatment apparatus including a washing tub configured to receive laundry, the washing tub being configured to be rotatable, a motor configured to rotate the washing tub, a controller configured to control the motor, and a current sensing unit configured to sense current of the motor.

The controller may control the motor such that the washing tub is accelerated to a predetermined target speed. In particular, the controller may perform control such that the washing tub is accelerated at an acceleration gradient of 1.5 to 2.5 rpm/s.

The laundry treatment apparatus may further include a current sensing unit configured to sense current of the motor, wherein the controller may be configured to obtain at least one of laundry weight or laundry quality from output of an output layer of an artificial neural network pre-trained based on machine learning using a current value sensed by the current sensing unit during accelerated rotation of the washing tub as input of an input layer of the artificial neural network.

The acceleration gradient may be 2.0 rpm/s.

The acceleration gradient may be the minimum value controllable by the controller.

The acceleration gradient may be maintained at a uniform value until the motor is accelerated to the target speed.

The controller may be configured to determine laundry constraint based on the output of the output layer.

When the washing tub is rotated one or more revolutions in one direction in a rotational speed period of the washing tub in which the current value as the input data is obtained, laundry located at the lowermost side in the washing tub may be raised to a predetermined height by rotation of the washing tub and may then be dropped while being separated from the washing tub.

The laundry treatment apparatus may further include a speed sensing unit configured to sense the rotational speed of the motor, wherein the controller may be configured to select a current value corresponding to a period in which the rotational speed of the motor is accelerated from a first rotational speed to the target speed from among current values obtained by the current sensing unit based on a speed value sensed by the speed sensing unit and to use the selected current value as the input data.

The target speed may be 60 to 80 rpm.

The first rotational speed may be 10 to 20 rpm.

In accordance with another aspect of the present invention, there is provided a method of controlling a laundry treatment apparatus, the method including (a) a step of accelerating a washing tub having laundry introduced thereinto to a predetermined target speed at an acceleration gradient of 1.5 to 2.5 rpm/s within a range within which the laundry moves in the washing tub, (b) a step of obtaining a current value of a motor configured to rotate the washing tub in a period in which the washing tub is rotated while being accelerated, and (c) a step of obtaining at least one of laundry weight or laundry quality from output of an output layer of an artificial neural network pre-trained based on machine learning using the current value as input of an input layer of the artificial neural network.

The acceleration gradient may be 2.0 rpm/s.

The acceleration gradient may be the minimum value controllable by a controller.

The acceleration gradient may be maintained at a uniform value until the motor is accelerated to the target speed.

The method may further include a step of determining laundry constraint based on the output of the output layer.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a side sectional view showing a laundry treatment apparatus according to an embodiment of the present invention;

FIG. 2 is a block diagram showing a control relationship between main components of the laundry treatment apparatus of FIG. 1;

FIG. 3 is a view showing the pattern of current supplied to a motor based on laundry quality and load weight (laundry weight);

FIG. 4 is a view showing the pattern of current by laundry quality;

FIG. 5 is a view showing the pattern of current by load in the state in which the speed of a motor is controlled using a predetermined method;

FIG. 6 is a view showing a process of processing present current values obtained by a current sensing unit as input data of an artificial neural network;

FIG. 7 is a brief view showing an example of the artificial neural network;

FIG. 8 is a brief view showing a process of determining laundry quality by laundry weight using the present current value of the motor in the state of being divided into a learning process and a recognition process;

FIG. 9A is a graph showing the present current value sensed by the current sensing unit and FIG. 9B is a graph showing average values obtained by processing a moving average filter;

FIG. 10 is a graph showing current values sensed by the current sensing unit;

FIG. 11 is a graph showing values obtained by processing the current values of the graph shown in FIGS. 9A and 9B so as to be used as input data of the artificial neural network;

FIG. 12 is a flowchart showing a method of controlling the laundry treatment apparatus according to the embodiment of the present invention;

FIG. 13 is a graph showing current patterns by load in the state of overlapping each other;

FIG. 14 is a graph showing classification of current patterns corresponding to load of 0 to 6 kg in FIG. 13; and

FIG. 15 is a graph showing classification of current patterns corresponding to load of 7 to 9 kg in FIG. 13.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, the present invention is not limited to the following embodiments and may be implemented in various different forms.

Parts that are not related to the description of the present invention will be omitted from the drawings in order to clearly and briefly describe the present invention. Wherever possible, the same reference numbers will be used throughout the specification to refer to the same or like elements.

Meanwhile, the terms “module” and “unit,” when attached to the names of components, are used herein merely for convenience of description, and thus they should not be considered as having specific meanings or roles. Accordingly, the terms “module” and “unit” may be used interchangeably.

FIG. 1 is a sectional view showing a laundry treatment apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram showing a control relationship between main components of the laundry treatment apparatus according to the embodiment of the present invention.

Referring to FIG. 1, the laundry treatment apparatus according to the embodiment of the present invention includes a casing 1, which defines the external appearance thereof, a water storage tub 3 disposed in the casing 1 for storing wash water, a washing tub 4 rotatably installed in the water storage tub 3, laundry being introduced into the washing tub 4, and a motor 9 for rotating the washing tub 4.

The washing tub 4 includes a front cover 41 having therein an opening through which laundry is introduced and removed, a cylindrical drum 42 disposed approximately horizontally, the front end of the cylindrical drum 42 being coupled to the front cover 41, and a rear cover 43 coupled to the rear end of the drum 42. A rotary shaft of the motor 9 may be connected to the rear cover 43 through a rear wall of the water storage tub 3. A plurality of through-holes may be formed in the drum 42 such that water flows between the washing tub 4 and the water storage tub 3.

A lifter 20 may be provided at the inner circumferential surface of the drum 42. The lifter 20 may be formed so as to protrude from the inner circumferential surface of the drum 42, and may extend in the longitudinal direction (the forward-rearward direction) of the drum 42. A plurality of lifters 20 may be arranged in the circumferential direction of the drum 42 so as to be spaced apart from each other. When the washing tub 4 is rotated, laundry may be lifted up by the lifters 20.

However, the present invention is not limited thereto. The height of each lifter 20 protruding from the drum 42 is preferably 30 mm (or 6.0% of the diameter of the drum) or less, more preferably 10 to 20 mm. Particularly, in the case in which the height of each lifter 20 is 20 mm or less, the laundry may move without clinging to an inner surface of the washing tub 4 even when the washing tub 4 is continuously rotated in one direction at about 80 rpm. That is, when the washing tub 4 is rotated one or more revolutions in one direction, laundry located at the lowermost side in the washing tub 4 may be raised to a predetermined height by rotation of the washing tub 4 and may then be dropped while being separated from the washing tub 4.

The washing tub 4 is rotated about a horizontal axis. Here, “horizontality” does not mean geometric horizontality in the strict sense of the word. Even in the case in which the washing tub 4 is inclined at a predetermined angle to the horizontality, as shown in FIG. 1, the inclination of the washing tub 4 is approximate to the horizontality, rather than the verticality. Hereinafter, therefore, the washing tub 4 will be described as being rotated about the horizontal axis.

A laundry introduction port is formed in the front surface of the casing 1, and a door 2 for opening and closing the laundry introduction port is hinged to the casing 1. A water supply valve 5, a water supply pipe 6, and a water supply hose 8 may be installed in the casing 1. When the water supply valve 5 is opened in order to supply water, wash water passing through the water supply pipe 6 is mixed with detergent in a dispenser 7, and is then supplied to the water storage tub 3 through the water supply hose 8.

An input port of a pump 11 is connected to the water storage tub 3 via a discharge hose 10, and a discharge port of the pump 11 is connected to a drainage pipe 12. Water discharged from the water storage tub 3 through the discharge hose 10 is driven along the drainage pipe 12 by the pump 11, and is then discharged out of the laundry treatment apparatus.

Referring to FIG. 2, the laundry treatment apparatus according to the embodiment of the present invention may include a controller 60 for controlling the overall operation of the laundry treatment apparatus, a motor driving unit 71, an output unit 72, a communication unit 73, a speed sensing unit 74, a current sensing unit 75, and a memory 76, all of which are controlled by the controller 60.

The controller 60 may control a series of washing processes, such as washing, rinsing, spin drying, and drying. The controller 60 may perform washing and rinsing cycles according to a predetermined algorithm. In addition, the controller 60 may control the motor driving unit 71 according to the algorithm.

The motor driving unit 71 may control driving of the motor 9 in response to a control signal from the control unit 60. The control signal may be a signal for controlling the target speed, the acceleration gradient (or acceleration), the driving time, etc. of the motor 9.

The motor driving unit 71, which drives the motor 9, may include an inverter (not shown) and an inverter controller (not shown). In addition, the motor driving unit 71 may be a concept further including a converter for supplying direct-current power that is input to the inverter.

For example, in the case in which the inverter controller (not shown) outputs a pulse with modulation (PWM) type switching control signal to the inverter (not shown), the inverter (not shown) may perform a high-speed switching operation in order to supply alternating-current power having a predetermined frequency to the motor 9.

The speed sensing unit 74 senses the rotational speed of the washing tub 4. The speed sensing unit 74 may sense the rotational speed of a rotor of the motor 9. In the case in which planetary gear trains, which convert the rotation ratio of the motor 9 in order to rotate the washing tub 4, are provided, the rotational speed of the washing tub 4 may be a value obtained by converting the rotational speed of the rotor sensed by the speed sensing unit 74 in consideration of the deceleration or acceleration ratio of the planetary gear trains.

The controller 60 may control the motor driving unit 71 such that the motor follows the predetermined target speed using the present speed transmitted from the speed sensing unit 74 as feedback.

The current sensing unit 75 may sense current that is supplied to the motor (hereinafter referred to as present current), and may transmit the sensed present current to the controller 60. The controller 60 may sense laundry weight and laundry quality using the received present current as input data. At this time, present current values as the input data include values obtained while the motor 9 is accelerated to the predetermined target speed.

In the case in which the rotation of the motor 9 is controlled through vector control based on torque current and flux current, the present current may be a torque-axis (q-axis) component of current flowing in a motor circuit, i.e. torque current Iq.

The output unit 72 outputs the operation state of the laundry treatment apparatus. The output unit 72 may be an image output device that visually outputs images, such as an LCD or an LED, or a sound output device that outputs sound, such as a speaker or a buzzer. The output unit 72 may output information about the laundry weight or the laundry quality under the control of the controller 60.

The memory 76 may store a programmed artificial neural network, patterns of current by laundry weight and/or by laundry quality, a database (DB) constructed through machine-learning-based training based on the patterns of current, a machine learning algorithm, present current values sensed by the current sensing unit 75, an average of the present current values, a value obtained by processing the average according to a parsing rule, and data transmitted and received through the communication unit 73.

In addition, the memory 76 may store various control data for controlling the overall operation of the laundry treatment apparatus, washing setting data input by a user, washing time obtained according to washing setting, data about a washing course, and data for determining whether an error occurs in the laundry treatment apparatus.

The communication unit 73 may communicate with a server connected to a network. The communication unit 73 may include one or more communication modules, such as an Internet module and a mobile communication module. The communication unit 73 may receive various data, such as learning data and algorithm update, from the server.

The controller 60 may process various data received through the communication unit 73 in order to update the memory 76. For example, in the case in which data input through the communication unit 73 are update data about an operation program stored in the memory 76 in advance, the controller 60 may update the memory 76 using the same. In the case in which the input data are a new operation program, the controller 60 may also store the same in the memory 76.

Machine learning means that, although a human does not directly instruct logic to a computer, the computer learns through data and thus solves problems for itself therethrough.

Deep learning is a method of teaching a human's way of thinking to a computer based on an artificial neural network (ANN) for constructing artificial intelligence, and is artificial intelligence technology enabling the computer to autonomously learn like a human although the human does not teach the computer. The artificial neural network (ANN) may be realized in the form of software or hardware, such as a chip.

The laundry treatment apparatus may process current values sensed by the current sensing unit 75 in order to grasp the features of laundry introduced into the washing tub 4 (hereinafter referred to as laundry characteristics) based on machine learning. Examples of the laundry characteristics may include laundry weight and laundry quality. The controller 60 may determine laundry quality by laundry weight based on machine learning. For example, the controller 60 may obtain laundry weight, and may determine one of previously classified categories to which laundry belongs based on laundry quality. The laundry quality may be defined based on various factors, such as the material of laundry, the softness of laundry (e.g. soft laundry/hard laundry), the ability of laundry to contain water (i.e. water content), and the volumetric difference between dry laundry and wet laundry.

The controller 60 may sense laundry weight using the present current value sensed by the current sensing unit 75 until the target speed is reached as input data of the artificial neural network previously trained through machine learning.

FIG. 3 is a view showing the pattern of current supplied to the motor based on laundry quality and load weight (laundry weight). FIG. 4 is a view showing the pattern of current by laundry quality. FIG. 5 is a view showing the pattern of current by load in the state in which the speed of the motor is controlled using a predetermined method.

Graphs shown in FIG. 3 show present current measured while the washing tub 4 is accelerated to a predetermined target speed (e.g. 80 rpm). In these graphs, measurement was performed while the composition of laundry (i.e. the mixing ratio of soft laundry to hard laundry) and load weight were changed. That is, it is possible to grasp a change in the pattern depending on load weight from the graphs arranged horizontally. For example, in the case of the same composition of laundry, it can be seen that the maximum value of present current in the initial stage of acceleration of the washing tub 4 increases as load weight is increased. Consequently, it may be appropriate to use the initial data of the graphs in order to determine load weight (laundry weight).

It is possible to grasp a change in the pattern depending on the composition of laundry from the graphs arranged vertically. For example, in the case of the same load weight, it can be seen that the current value decreases as the percentage of hard laundry is increased and that this phenomenon is particularly prominent in the intermediate and last stage of acceleration of the washing tub 4, in the intermediate/last stage of rotation of the washing tub 4, or in a period in which the target speed is maintained. Consequently, it may be appropriate to adopt data necessary to obtain laundry quality after the period in which the data to be used to determine laundry weight are obtained.

FIG. 4 shows the pattern of present current by laundry composition (laundry quality). In FIG. 4, C0.0 indicates 100% of soft laundry, C0.25, C0.5, and C0.75 indicate that the ratio of soft laundry to hard laundry is 1:3, 1:1, and 3:1, respectively, and C1.0 indicates 100% of hard laundry. In each case, the total laundry weight (load weight) including both soft laundry and hard laundry is uniform.

The graphs show that, in the case in which laundry composition is changed, the pattern of present current is changed even though load weight is uniform. Consequently, classification according to laundry composition (or laundry weight) is possible based on machine learning of current pattern.

Sensing of laundry weight/laundry quality may be repeated a plurality of times. In this embodiment, sensing of laundry weight/laundry quality is repeated three times.

The controller 60 may set a washing algorithm, or may change the setting of the washing algorithm, according to each result of sensing of laundry weight/laundry quality, and may control the operation of the laundry treatment apparatus according to the set washing algorithm.

Graphs P1, P3, P5, P7, P9, and P15 shown in FIG. 5 indicate that laundry weight is 1, 3, 5, 7, 9, and 15 kg, respectively. Each of the graphs is generally formed such that the present current value is abruptly increased to a predetermined level in the initial stage of acceleration of the washing tub 4 and converges on a uniform value in the last stage of rotation of the washing tub 4. In particular, it can be seen that deviation in the present current value depending on laundry weight is prominent in the initial stage of acceleration of the washing tub 4.

The controller 60 may include a laundry weight/laundry quality learning module 61 and a laundry weight/laundry quality recognition module 62. The laundry weight/laundry quality learning module 61 may perform machine learning using the present current value sensed by the current sensing unit 75 or a value obtained by processing the present current value. The laundry weight/laundry quality learning module 61 may update the database stored in the memory 76 through machine learning.

Any one of unsupervised learning and supervised learning may be used as a learning method of the laundry weight/laundry quality learning module 61.

The laundry weight/laundry quality recognition module 62 may determine a level depending on laundry weight based on data trained by the laundry weight/laundry quality learning module 61. Determination of laundry weight may be work of classifying laundry introduced into the washing tub 4 into a predetermined plurality of laundry weight levels depending on weight (load).

In this embodiment, laundry weight is classified into five steps (levels). Load weight (kg) corresponding to each level is shown in Table 1 below. In addition, Table 1 statistically shows the number of members constituting a family in the case in which laundry having corresponding laundry weight is introduced into the laundry treatment apparatus for the family.

TABLE 1 Laundry weight (5 Number of family steps) Load weight members Level 1 0 to 1 kg 1 Level 2 1 to 3 kg 1 or 2 Level 3 3 to 5 kg 3 Level 4 5 to 6 kg 3 or more Level 5 6 kg or more

Determination of laundry quality serves to classify laundry introduced into the washing tub 4 based on predetermined criteria. The criteria may include the material of laundry, the softness or hardness of laundry, the water content of laundry, and the volumetric difference between dry laundry and wet laundry.

The laundry weight/laundry quality recognition module 62 may determine one of the laundry weight levels to which laundry introduced into the washing tub 4 corresponds and one of the laundry quality steps to which the laundry corresponds (i.e. laundry quality by laundry weight) based on the present current value obtained from the current sensing unit 75.

Laundry quality (5 Wear degree/Washing steps) strength Kind Level 1 Wear degree: high Clothes made of Washing strength: light and soft low materials and Level 2 Mixture of level 1 underwear made of laundry and level 3 delicate materials laundry (e.g. silk) Level 3 Wear degree: middle Cotton-spun outer Washing strength: garments and middle cotton-spun/mixed- spun underwear Level 4 Mixture of level 3 Clothes made of laundry and level 5 thick materials, laundry coarse materials, Level 5 Wear degree: low and hard materials Washing strength: (e.g. autumn high jumpers, winter jumpers, and work clothes)

The laundry weight/laundry quality recognition module 62 may be equipped with an artificial neural network (ANN) trained in advance based on machine learning. The artificial neural network may be updated by the laundry weight/laundry quality learning module 61.

The laundry weight/laundry quality recognition module 62 may determine laundry weight and laundry quality based on the artificial neural network. In the case in which laundry weight is classified into five steps, as in this embodiment, the laundry weight/laundry quality recognition module 62 may determine the level to which laundry weight belongs, and may also determine the level to which laundry quality belongs, using the present current value sensed by the current sensing unit 75 as input data of the artificial neural network (ANN).

The laundry weight/laundry quality recognition module 62 may include an artificial neural network (ANN) trained to classify laundry weight and laundry quality based on predetermined criteria. For example, the laundry weight/laundry quality recognition module 62 may include a deep neural network (DNN) trained based on deep learning, such as a convolutional neural network (CNN), a recurrent neural network (RNN), and a deep belief network (DBN).

The recurrent neural network (RNN) may have an artificial neural network structure that is frequently used in natural language processing and the like and is effective for processing time-series data which vary over time and that is formed by building up layers at each instance.

The deep belief network (DBN) has a deep learning structure formed by stacking multiple layers of a restricted Boltzmann machine (RBM), which is a deep learning technique. The deep belief network (DBN) may have a predetermined number of layers formed by repeating restricted Boltzmann machine (RBM) learning.

The convolutional neural network (CNN) is a model mimicking a human brain function, built on the assumption that, when a person recognizes an object, the brain extracts basic features of the object and recognizes the object based on the result of complex processing in the brain.

Meanwhile, the artificial neural network may be trained by adjusting connection weights between nodes (if necessary, adjusting bias values as well) so as to produce desired output from given input. The artificial neural network may continuously update the weight values through learning. Methods such as back propagation may be used in training the artificial neural network.

The laundry weight/laundry quality recognition module 62 may determine at least one of laundry weight and laundry quality of laundry introduced into the washing tub 4 from output of an output layer using the present current value as input data and based on weights between nodes included in the deep neural network (DNN).

FIG. 7 is a brief view showing an example of the artificial neural network. FIG. 8 is a brief view showing a process of determining laundry quality by laundry weight using the present current value of the motor in the state of being divided into a learning process and a recognition process. Hereinafter, a description will be given with reference to FIGS. 7 and 8. Deep learning, which is a subfield of machine learning, enables data-based learning through multiple layers.

Deep learning may exhibit a collection of machine learning algorithms that extract core data from a plurality of data through a sequence of hidden layers.

The deep learning structure may include an artificial neural network (ANN). For example, the deep learning structure may include a deep neural network (DNN), such as a convolutional neural network (CNN), a recurrent neural network (RNN), and a deep belief network (DBN).

Referring to FIG. 7, the artificial neural network (ANN) may include an input layer, hidden layers, and an output layer. The deep neural network (DNN) includes a plurality of hidden layers. Each layer includes a plurality of nodes, and each layer is related to the next layer. The nodes may be connected to each other while having weights.

Output from an arbitrary node belonging to a first hidden layer (hidden Layer 1) becomes input to at least one node belonging to a second hidden layer (hidden Layer 2). At this time, input to each node may be a value obtained by applying a weight to output from a node of the previous layer. A weight may mean connection strength between nodes. The deep learning process may be a process of discovering an appropriate weight.

A well-known facial recognition process will be described for better understanding of deep learning. A computer may distinguish between bright pixels and dark pixels depending on the brightness of pixels, may distinguish between simple forms, such as contours and edges, and may distinguish between complicated forms and objects from an input image. Finally, the computer may grasp a form prescribing the face of a human. Materialization of such a feature (prescription of the facial form of the human) is finally obtained from the output layer through a plurality of hidden layers.

The memory 76 may store input data for sensing laundry weight and data necessary to train the deep neural network (DNN). The memory 76 may store motor speed data acquired by the sensing unit and/or speed data in the state of being added or processed by predetermined period. In addition, the memory 76 may store weights and biases constituting a deep neural network (DNN) structure.

Alternatively, in some embodiments, the weights and biases constituting the deep neural network structure may be stored in a memory embedded in the laundry weight/laundry quality recognition module 62.

Meanwhile, the laundry weight/laundry quality learning module 61 may perform learning using the present current value sensed by the current sensing unit 75 as training data. That is, whenever recognizing or determining laundry weight and/or laundry quality, the laundry weight/laundry quality learning module 61 may add the result of determination to the database in order to update the deep neural network (DNN) structure, such as weights or biases. Alternatively, after training data are secured a predetermined number of times, the learning process may be performed using the secured training data in order to update the deep neural network (DNN) structure, such as weights.

The laundry treatment apparatus may transmit data about the present current acquired by the current sensing unit 75 to a server (not shown) connected to a communication network through the communication unit 73, and may receive data related to machine learning from the server. In this case, the laundry treatment apparatus may update the artificial neural network based on the data related to machine learning received from the server.

FIG. 9A is a graph showing the present current value sensed by the current sensing unit and FIG. 9B is a graph showing average values obtained by processing a moving average filter. FIG. 10 is a graph showing current values sensed by the current sensing unit. FIG. 11 is a graph showing values obtained by processing the current values of the graph shown in FIGS. 9A and 9B so as to be used as input data of the artificial neural network. FIG. 12 is a flowchart showing a method of controlling the laundry treatment apparatus according to the embodiment of the present invention. Hereinafter, the method of controlling the laundry treatment apparatus according to the embodiment of the present invention will be described with reference to FIGS. 9A to 12.

The controller 60 performs control such that the motor 9 is rotated at a predetermined target speed (S1, S2, S4, and S5). During rotation of the motor 9, the rotational speed of the washing tub 4 (or the motor 9) is sensed by the speed sensing unit 74 (S2).

The target speed may be set as a rotational speed of the washing tub 4 at which the state in which laundry clings to the drum 42 can be maintained when the washing tub 4 is continuously rotated one or more revolutions in one direction while maintaining the target speed. The target speed may be 60 to 80 rpm, preferably, 80 rpm. Preferably, in the state before the rotational speed of the washing tub 4 reaches the target speed, the laundry moves in the drum 42 (e.g., the laundry is raised to a predetermined height and then separated from an inner surface of the washing tub 4 and is dropped by rotation of the drum 42).

Meanwhile, the target speed may be set based on the state in which water is supplied into the water storage tub 3 and thus a portion of the washing tub 4 is immersed in the water. That is, the laundry may move when the washing tub 4 is rotated at the target speed in the state in which a portion of the washing tub 4 is immersed in the water. In other words, during rotation of the washing tub 4, the laundry does not constantly cling to the drum 42 but may be raised to a predetermined height and then dropped.

The present current values used to determine laundry weight and laundry quality include values adopted in a period in which the laundry moves during rotation of the washing tub 4. That is, the controller 60 may adopt the present current values that are necessary based on the rotational speed of the washing tub 4 (or the rotational speed of the motor 9) sensed by the speed sensing unit 74.

Specifically, the controller 60 commands the motor driving unit 71 to accelerate the motor 9, and, when the rotational speed sensed by the speed sensing unit 74 reaches a predetermined first rotational speed V1, may store the present current value from that time in the memory 76 (S3 and S4).

When the washing tub 4 is in a stopped state, force applied to the laundry includes gravity and normal force generated by the inner surface of the drum 42, and these two forces are in equilibrium. When the washing tub 4 is rotated, the force of the lifters 20 in the rotational direction of the washing tub 4 is applied to the laundry.

Meanwhile, in the case in which laundry weight is large, the force of the lifters 20 may not be directly applied to some of the laundry. In the case in which the rotational speed of the washing tub 4 is equal to or less than a predetermined speed, some of the laundry may not move although the washing tub 4 is rotated. Alternatively, even in the case in which the washing tubs 4, in which laundry having the same weight and made of the same material is received, are rotated at the same speed, the laundry may move differently due to various factors, such as the position of the laundry in the washing tub 4.

That is, in the initial stage of an acceleration period of the motor 9, various factors, such as the position of the laundry in the washing tub 4, may be excessively reflected in the current value applied to the motor 9, in addition to laundry weight and laundry quality. The first rotational speed V1 may mean the predetermined speed.

Preferably, therefore, the initial current value in the acceleration period is excluded as input data for determining laundry weight and laundry quality. The current value until the rotational speed V of the motor 9 reaches the first rotational speed V1 may not be used as input data, and the current value sensed after the rotational speed V of the motor 9 reaches the first rotational speed V1 may be used as input data.

The first rotational speed V1 may be lower than a second rotational speed V2, and may be a rotational speed at which the laundry moves in the washing tub 4. The first rotational speed V1 may be 10 to 20 rpm. In the case in which the washing tub 4 is rotated at a speed lower than 10 rpm, the laundry may not move in the washing tub 4. The laundry in the washing tub 4 starts to move when the rotational speed of the washing tub 4 is about 10 rpm, and moves in the washing tub 4 irrespective of laundry weight when the rotational speed V of the washing tub 4 reaches 20 rpm. In this embodiment, the first rotational speed is set to 20 rpm.

When the rotational speed V of the washing tub 4 reaches the predetermined second rotational speed V2, the controller 60 may not store the present current value any longer, and may process the present current value (S5 and S6). Here, the second rotational speed V2 is the target speed.

Meanwhile, the acceleration gradient from the first rotational speed V1 to the second rotational speed V2 may be uniform. Preferably, the acceleration gradient is maintained uniform in order to improve reliability in sensing a change in the pattern of current.

The acceleration gradient must not be too high such that a change in the movement of laundry in the washing tub 4 is clearly exhibited. The acceleration gradient is preferably 1.5 to 2.5 rpm/s, more preferably 2.0 rpm/s. However, the present invention is not limited thereto. The acceleration gradient may have a smallest possible value within a range controllable by the controller 60.

As shown in FIG. 6, processing of the present current value is a process of processing the present current values Iq obtained at predetermined points of time according to a predetermined algorithm in order to generate input data In1, In2, In3, In4 . . . of the input layer of the artificial neural network (S6).

This process may include a step of obtaining the average of the present current values Iq and a step of processing the obtained average values according to a predetermined parsing rule in order to generate input data of the artificial neural network. In particular, the number of input data processed according to the parsing rule is less than the number of average values.

Referring to FIG. 8, the controller 60 may acquire current values at predetermined time intervals through the current sensing unit 75. In this embodiment, a total of 545 present current values are obtained at predetermined time intervals in a period in which the rotational speed of the washing tub 4 is accelerated from the first rotational speed V1 to the second rotational speed V2.

The controller 60 may average the present current values thus obtained in every predetermined time period. At this time, the controller 60 may use a moving average filter. Moving average is obtaining an average while changing a period such that a change can be seen. For example, on the assumption that the present current values are Iq1, Iq2, Iq3 . . . Iqn in a time-series sequence, Iq1 to Iql (1<n) are averaged to obtain M1, and Iqm (m>1) to Iqm+s−1 (s being the number of Iq used to obtain each moving average) are averaged to obtain M2. In this way, moving averages may be obtained while continuously changing a period.

In the case in which time periods in which the moving average is obtained are appropriately set, the number of moving average values M1, M2 . . . may be less than the number of total present current values Iq. As the length of a time period (window) is increased, however, the resolution of a change in the present current is lowered. Therefore, it is necessary to appropriately select the length of the time period. In this embodiment, the controller 60 obtains 50 moving averages from 545 present current values Iq using the moving average filter.

The controller 60 may process the present current values and the moving averages according to the predetermined parsing rule in order to generate input data In1, In2, In3, In4 . . . . The parsing rule may be configured to select a period in which final input data are obtained such that features (laundry weight/laundry quality) to be obtained are well exhibited.

In this embodiment, a total of 14 input data are generated, and the input data include 9 present current values DATA1 to DATA9 obtained at the initial stage of acceleration of the motor 9 (16^(th) to 24^(th) present current values) and five average values DATA10 to DATA14 in subsequent periods divided according to a predetermined condition. In particular, the five average values are obtained based on the previously obtained moving averages, whereby it is possible to process the operation more rapidly than adding the present current values in respective periods. Meanwhile, input data In1, In2, In3, In4 . . . In14 thus obtained become the input values of respective nodes of the input layer.

Weights and biases assigned to nodes constituting the artificial neural network are set through machine learning. Such machine learning is repeated based on a current pattern or present current values. In addition, since the characteristics about laundry weight and/or laundry quality are reflected in the current pattern (or the present current value) as described above, machine learning may be performed on data that are previously stored or added by operation of the laundry treatment apparatus until an accurate result (i.e. accurate laundry weight and laundry quality of laundry introduced into the washing tub 4) is derived, whereby it is possible to set improved or accurate weights and biases.

In the artificial intelligence network constructed as described above, laundry weight-laundry quality information may be reflected in the output of the output layer, and the controller 60 may determine laundry weight and/or laundry quality based on a node that outputs the largest value, among the nodes of the output layer.

The controller 60 may input the input data generated at step S6 into the artificial neural network in order to obtain laundry weight and/or laundry quality from the output of the output layer (S7). Subsequently, the controller 60 may set a washing algorithm based on the laundry weight and/or laundry quality obtained at step S7, and may control the operation (running) of the laundry treatment apparatus according to the set washing algorithm (S8). The washing algorithm may include a water supply level, washing time, rising time, spin-drying time, and drying time, and a motor driving pattern in each cycle (e.g. a rotational speed, rotation time, acceleration, and braking).

FIG. 13 is a graph showing current patterns by load in the state of overlapping each other. FIG. 14 is a graph showing classification of current patterns corresponding to load of 0 to 6 kg in FIG. 13. FIG. 15 is a graph showing classification of current patterns corresponding to load of 7 to 9 kg in FIG. 13. Hereinafter, a description will be given with reference to FIGS. 13 to 15. P0 to P9 shown in these figures indicate load weight (laundry weight) of 0 to 9 kg.

Laundry may be constrained by the door 2. This phenomenon may occur in the case in which a large weight of laundry is introduced into the washing tub 4, whereby the laundry comes into tight contact with or interferes with the door 2. The constraint of the laundry affects the load applied to the motor 9. In the process of determining laundry weight and/or laundry quality, therefore, it is preferable to exclude the present current value obtained while the washing tub 4 is rotated (or accelerated) in the state in which the laundry is constrained.

Referring to FIGS. 14 and 15, current patterns P0 to P6 when the load weight is 0 to 6 kg and current patterns P7 to P9 when the load weight is 7 to 9 kg are quite different from each other. That is, in the case of a large weight of laundry (in this embodiment, 7 to 9 kg), it can be seen that the present current value is periodically increased and decreased (or fluctuated) at the initial stage of acceleration of the washing tub 4. The reason for this is that, when some of the laundry is constrained by the door 2 and the washing tub 4 interferes with the constrained laundry, the load of the motor 9 is increased and that, when the interference is weakened or removed, the load of the motor 9 is decreased. That is, a change in the load of the motor 9 due to the constraint of the laundry occurs in response to the rotational cycle of the washing tub 4.

Such a load change pattern may be learned through machine learning, and the learning result may be stored in the memory 76 in the form of a database. An artificial neural network may be constructed using the learning result. The controller 60 may determine laundry constraint (or laundry catching) through the output of the output layer based on the artificial neural network thus constructed.

Although the above description has been made by way of example based on a front load type laundry treatment apparatus, in which the washing tub 4 is rotated about a substantially horizontal axis, the laundry treatment apparatus according to the present invention and the method of controlling the same may be applied to a top load type laundry treatment apparatus.

Meanwhile, the method of controlling the laundry treatment apparatus according to the embodiment of the present invention may be implemented as code that can be written on a processor-readable recording medium and thus read by a processor. The processor-readable recording medium may be any type of recording device in which data is stored in a processor-readable manner. The processor-readable recording medium may include, for example, read only memory (ROM), random access memory (RAM), compact disc read only memory (CD-ROM), magnetic tape, a floppy disk, and an optical data storage device, and may be implemented in the form of a carrier wave transmitted over the Internet. In addition, the processor-readable recording medium may be distributed over a plurality of computer systems connected to a network such that processor-readable code is written thereto and executed therefrom in a decentralized manner.

As is apparent from the above description, the laundry treatment apparatus according to the present invention and the method of controlling the same are capable of setting the acceleration gradient of a washing tub to a relatively small value of 1.5 to 2.5 rpm/s when rotating the washing tub while accelerating the washing tub in order to sense laundry weight/laundry quality such that the movement characteristics of laundry by laundry weight or by laundry quality are clearly exhibited during the above process. Consequently, the movement characteristics of the laundry by laundry weight or by laundry quality may be minutely reflected in a current pattern of a motor during acceleration of the washing tub. In addition, the current pattern data may be input to an artificial neural network based on machine learning, whereby it is possible to accurately grasp information about the laundry, such as laundry weight or laundry quality.

In particular, the classification of the laundry by characteristic is possible based on various criteria, such as the material of the laundry, the water content of the laundry, the volumetric difference between dry laundry and wet laundry, in addition to the laundry weight. In addition, accuracy may be further improved with accumulation of training data (motor current data) of machine learning.

It will be apparent that, although the preferred embodiments have been shown and described above, the present invention is not limited to the above-described specific embodiments, and various modifications and variations can be made by those skilled in the art without departing from the gist of the appended claims. Thus, it is intended that the modifications and variations should not be understood independently of the technical spirit or prospect of the present invention. 

What is claimed is:
 1. A laundry treatment apparatus comprising: a washing tub configured to receive laundry, the washing tub being configured to be rotatable; a motor configured to rotate the washing tub; a controller configured to control the motor such that the washing tub is accelerated to a target speed at an acceleration gradient of 1.5 to 2.5 rotations per minute per second (rpm/s)within a range of rotation of the washing tub in which the laundry is separated from an inner surface of the washing tub; and a current sensing unit configured to sense an electrical current value of the motor, wherein the controller is configured to obtain at least one of a laundry weight or a laundry quality by an output of an output layer of a pre-trained machine-learning network based on an input to an input layer of the machine-learning network that comprises the electrical current value sensed by the current sensing unit during an accelerated rotation of the washing tub.
 2. The laundry treatment apparatus according to claim 1, wherein the acceleration gradient is 2.0 rpm/s.
 3. The laundry treatment apparatus according to claim 1, wherein the acceleration gradient is a minimum value for accelerating the washing tub that is controllable by the controller.
 4. The laundry treatment apparatus according to claim 1, wherein the acceleration gradient is maintained at a uniform value until the motor is accelerated to the target speed.
 5. The laundry treatment apparatus according to claim 1, wherein the controller is further configured to determine a laundry constraint based on the output of the output layer of the machine-learning network.
 6. The laundry treatment apparatus according to claim 1, wherein, based on the washing tub being rotated by one or more revolutions in a first direction within a range of rotation of the washing tub in which the electrical current value that is input to the machine-learning network is sensed by the current sensing unit: the laundry that is located at a lowermost position in the washing tub is raised to a first height by the rotation of the washing tub and is then dropped while being separated from the inner surface of the washing tub.
 7. The laundry treatment apparatus according to claim 1, further comprising: a speed sensing unit configured to sense a rotational speed of the motor, wherein the controller is further configured to: select, from among a plurality of electrical current values obtained by electrical current sensing unit and based on the rotational speed of the motor sensed by the speed sensing unit, the electrical current value corresponding to a period in which the rotational speed of the motor is accelerated from a first rotational speed to the target speed; and use the selected electrical current value as the input to the machine-learning network.
 8. The laundry treatment apparatus according to claim 7, wherein the target speed is 60 rotations per minute (rpm) to 80 rpm.
 9. The laundry treatment apparatus according to claim 7, wherein the first rotational speed is 10 rpm to 20 rpm.
 10. A method of controlling a laundry treatment apparatus, the method comprising: accelerating a washing tub having laundry introduced thereinto to a target speed at an acceleration gradient of 1.5 to 2.5 rotations per minute per second (rpm/s) within a range of rotation of the washing tub within which the laundry is separated from an inner surface of the washing tub; obtaining an electrical current value of a motor that is configured to rotate the washing tub, wherein the electrical current value is obtained during an accelerated rotation of the washing tub; and obtaining at least one of a laundry weight or a laundry quality by an output of an output layer of a pre-trained machine-learning network based on an input to an input layer of the machine-learning network that comprises the electrical current value.
 11. The method according to claim 10, wherein the acceleration gradient is 2.0 rpm/s.
 12. The method according to claim 10, wherein the acceleration gradient is a minimum value for accelerating the washing tub that is controllable.
 13. The method according to claim 10, wherein the acceleration gradient is maintained at a uniform value until the motor is accelerated to the target speed.
 14. The method according to claim 10, further comprising: determining a laundry constraint based on the output of the output layer of the machine-learning network. 